Process of treating iron ores



April 18, 1933. E. w. wEsco'rTv 1,904,583

PROCESS OF TREATING IRON CRES Filed 001'.. 24, 1929 BY we/*4% t7%ATTZl/aYS Patented Apr. 18, 1933 UNITED STATES PATEN'I.V OFFICE ERNESTW. WESCOTT, 0F NIAGARA FALLS, NEW YORK, AMSSIGNOR, BY MESNE .ASSIGN- iMENTS, TO SULPHIDE CORPORATION, A CORPORATION OF DELAWAREv PROCESS OFTREATING IRON ORES Application led October 24, 1929. SeraI No. 402,010.

This invention relates to an improved chlorination process for therecovery of iron oxid and other values, including sulfur when present,from ores of, or containing, iron, and in particular to a modified formof the split cycle process described and claimed in my co-pendingapplication Ser. No. 254,805.y

In my co-pending application above mentioned, I have described anembodiment of the split cycle process in which the several steps ofchlorinating a sulfid ore to displace and volatilize the sulfur withformation of ferrous chlorid, further chlorinating the ferrous chloridto ferrie chlorid, and burning the ferrie chlorid as vapors with air toform ferrie oxid and liberate the chlorin for re-use, are carried on ina continuous manner with voidance from the system with the sulfur of anamount of inert gases (nitrogen, CO2, etc.) equal to that introducedwith the air, and producer gas when used, in the ferrie chlorid burningstep. This is made possible by 'carrying on the sulfur-displacing stepandthe ferrous chlorid-'chlorination step in separate and distinctreaction chambers or zones, and at a suitable point in the iiow ofdilute gaseous chlorinating agent dividing the stream and leading thesub-Hows thereof to the respective zones above mentioned, recovery forre-use in the cycle of chlorinfrom its combination with the iron beingeffected by leading ferrie chlorid vapors from the ferrous chloridclilorinating zone directly, without condensation to void inert gasesmixed therewith, to the ferrie chlorid burning zone. Since at leasttwice as much chlorin is required in the sulfur-displacing step as inthe ferrous chlorid chlorinating step, it follows that the sub-flow ledto the sulfur-displacing zone will always carry at least twice as muc-hinert gases as are returned to the oXidizer with the ferrie chloridvapors coming from the ferrous chlorid chlorination Zone. The inertgases led to the sulfur-displacing zone are voided from the system withthe sulfur and hence after a short period of operation a balance will bereached between the amount of inert gases introduced at the oxidizer andthe amount voided with vthe sulfur. t

According to the specic form of the split cycle disclosed in myco-pending application above mentioned, the stream lof dilute chlorincoming from the oxidizer is divided into a major sub-flow and a minorsub-flow, proportioned according to lthechlorin requirementsrespectivelyy of the sulfur-displacing step and the ferrous chloridchlorinating step. The majorv sub-flow is utilized either directly inthe sulfur-displacing step or first passed over sulfur, thereby formingsulfur chlorid which is used in such step. The minor sub-flowis leddirectly to the ferrous chlorid chlorination zone where the chlorincontained therein is reacted under proper temperature conditions uponthe ferrousl chlorid converting same into ferrie chlorid vapors, whichtogether with the residual inert gases introduced with the chlorin areled to the oxidizer. and burned.

Owing to the dilute condition of the chlorinating agent thevolatilization of the displaced sulfur takes place at a temperatureconsiderably below the vnormal boiling point of sulfur. With thedilution-obtainedy by the use of air in the ferrie chlorid burning step,volatilization can be lmaintained at temperatures around 300 C. andordinarily when the operation is conducted with su1' fur vapors leavingthe system between 320 and 350 C. and the amount of chlorinating agentused .in the sulfur-displacing lstepI is merely enough to effect thedisplacement of the sulfur and the formation of ferrous chlorid suchvapors will be free from ferrous and ferrie chlorids and may be easilycondensed and recovered in 'a pure state.

According to the present invention, the advantages of the split cycleare obtained by splitting the flow of gaseous chlorinating agent at adifferent point in the cyclethan proposed in the prior application.` Tobe specific, instead of burning all of the ferrie As in the priorapplication, when treating sulfid ores the temperatures maintained inthe sulfur-displacing zone are so controlled as to insure volatilizationof the sulfur freed lfrom its combination with iron. The sulfur vaporsmixed with the inert gases introduced with the ferrie chlorid vapors areled olf and condensed or otherwise utilized.

The remainder of the ferrie chlorid is led directly as vapors to theoxidizer and burned with air producing ferrie oxid and liberatingchlorin for re-use. Y

The ferrous'chlorid formed in the sulfurdisplacing step, togetherwiththe gangue and any non-ferrous metal chlorids and values present inthe ore, is led to the second reaction chamber or zone (the ferrouschlorid chlorinating zone) where it is contacted with the chlorinrecovered from the minor sub-How as above described, under suchtemperature conditionsthat the ferrie chlorid formed is volatilizedl andremovedf It is then split into two streams, and the split cycle isrepeated.

In order better to illustrate my invention, I have shown in theaccompanying drawing aflow sheet depicting the course of travel of thematerials. i At -10 I have shown. a chamber in which the first stage ofchlorination-that is to say, contacting of the raw ore with ferricchlorid-is carried on. Ground dry ore or concentrate, or any4 raw sulidmaterial of choice, is fed into the chamber as indicated by the arrow. Astream of dilute ferrie chlorid vapors is fed in through pipe A12, froma source to be later described. The orethus flows in countercurrent tothe stream of chlorinating agent. The ferricchlorid very soon becomesfixed as ferrous chlorid, according to the equationabove. As in theprocess described inv my co-pending application above mentioned,ltemperatureconditions in the'chamber 10 are ordis narily so'controlledthat a temperature is maintained sufficient to effect volatilization ofthe liberated sulfur but insuf'icient to effect anydsubstantialvolatilization of the ferrous chlorid formed. However, the use ofvtemperatures suiiicient to effect partial vaporization of the ferrouschlorid is not preeluded and for some purposes and when'the process isbeing conducted without requiring extreme purity of the sulfur directlyproduced, this may be permissible. f

The mixture of inert gases and sulfur vapors may be withdrawnfrom thechamber l() through a pipe 14 and then led through a dust chamber 16into a sulfur condenser 18. This condenser may consist of the generaltype of a tubular boiler such as described and claimed in my co-pendingapplication Serial No. 368,568, in which the sulfur vapors are contactedwith water-.cooled surfaces maintained at a temperature corresponding toa steam pressure of fromr2to just below l6 atmospheres (absolutepressure) The sulfur condensing within this temperature range is not hotenough to be viscid and runs freely. As indicated in the drawing thepure liquid sulfur iswithdrawn at 20, the waste gases at 22 and lowpressure steam at 24.

The vferric chlorid introduced at`12'is,`as has been explained, justsuflicient to convert all of the iron of the ore to the ferrous form, sothat as the material reaches the discharge end of the chamber 10 it willconsist of ferrous chlorid, mixed with chlorids of such other metalvalues as may -be present in the ore, and the gangue constituents ifany. This material, in the solid state,.is transferred preferablywhilehot toV chamber 26, through conduit 28. This chamber represents thesecond stage of chlorination, wherein ythe solid ferrous chlorid isconverted into the volatile ferric salt.y At 30, an incoming stream ofchlorin diluted with inert gases,'meets the descending stream ofpartially chlorinated material. Ferric chlorid is formed, which, beingvolatile at the temperature of operation, passes out with the inertgases through conduit 32. This conduit 32 splits into two conduits, one,12, which passes to chamber 10, where it supplies ferrie chlorid as thechlorinating'agent for the raw ore, and a second conduit 34. yTherelationship between these conduits is such that 12 carries sub#stantially two-thirds of the output of conduit 32', while 34 carries theremaining onethird. Conduit 34 leads to a dust chamber'y 36, and fromthence the vapors are led by way of a conduit to an oxidizer orcombustion chamber 38.

In the oXidiZer, the ferrie chlorid, still in vapor form, is burned withpreheated air, introduced through 40. Hydrogen-free producer gas may beadded, as at 42, if desired, to furnishl additional heatv and produce acoarse massive product. In this event, the quantity of air is regulatedto secure combustion of the producer gas.` Solid ferri'c oxid is formedand is-.discharged and'collected at 44. The chlorin, mixed with residualaircomponents and producer gas combustion products, leaves theoxidizerat 46, passes through a dust chamber 48, andV is introduced at 30 intochamber 26,` tocomplete the second stage of the process. Vhile intheory, the chlorin travels in a completely closed cycle, without loss,in practice, metals other than iron will lcause a gradual removal of thechlorinfas chloride, being discharged from the system at 50. In order tocompensate for this loss, additional or make-up chlorinl may beintroduced as needed at 52, or at any other suitable point. Ifintroduced at l2, the makeuplchlorin may be in the form of sulfurchloric f Kiln 1() may be of any construction insuring intimacy ofContact between the gaseous chlorinating agent and the raw ore; detailsthereof are unimportant, eXcept that it shall be long enough to permitall of the ferrie chlorid introduced to be reduced to the ferrous statebefore reaching the sulfur vapor outlet. 'Ihe second kiln 26, issufficiently large, compared with kiln l0, so that all the ferrouschlorid furnished it can be converted to ferrie chlorid and nounconverted ferrous chlorid can pass out with the gangue.

As mentioned more generally above, both in the process described in myprior co-pending application Ser. No. 254,805 and the presentapplication the stream of chlorinating gases is split in the course ofthe cycle into a major and a minor sub-flow. In the former, the divisionis effected after all of the ferrie chlorid has been passed to theoXidiZer and involves the splitting of a stream of dilute chlorin, whilein the latter the stream of ferric chlorid is split, and this at a pointin the cycle before lthe ferric chlorid burning stage is reached. Inboth instances the major and minor sub-flows bear the same relation toeach other; that is, the major sub-flow constitutes two-thirds and theminor sub-flow one-third of the dilute chlorin or ferrie chlorid vapors,as the case may be, when no non-ferrous chlorinatable values are presentand with a still greater predominance of the major sub-flow if suchvalues are present.

While I have more specifically described the treatment of sulfid ores,the invention as hereinbefore more generally indicated, also applies tothe treatment of oXid ores. In treating oXid ores, sufficient reducingmaterial, such as carbon substantially free from hydrogen, is added toinsure reduction of the iron to the metallic state so that when it iscontacted with the hot ferric chlorid vapors coming forward from thelater ferrie chlorid chlorinating step, chlorination of the reduced ironto the ferrous chlorid state will proceed smoothly. The reactions thattake place may be written thus:

In some cases it may be convenient to reduce the iron oXid of the oremore or less completely previously to the chlorinating step.

The ferrous chlorid produced in the first chlorinating step abovedescribed is led to the ferrous chlorid chlorinating Zone, and furtherchlorinated to ferrie chlorid vapors which are in part burned and inpart recycled as in the treatment of sulfid ores.

Under the term sulfid ore I mean to iner thanl limiting, might be shown;and such changes are 'to be considered as included in my invention,which is limited only by the prior art and the scope of the appendedclaims.

I claim: Y

l. A cyclic process for treating materials containing iron for-therecovery therefrom of contained valuesv which comprises treating such amaterial in a first step with dilute ferrie chlorid vapors to `convertthe iron to ferrous chlorid, the temperature in saidfirst step beingmaintained above that temperature at which ferrie chlorid willcondensefrom the dilute vapor mixture brought to said step and at the same timesufiicient to insure volatilization of any sulfur freed in said firststep; voiding the inert -gas accompanying the ferrie chlorid used inthis first step of conversion from the cycle; then treating the ferrouschlorid in a second step of conversion with dilute chlorin to formferrie chlorid vapors, and burning part of the ferrie chlorid vapors soformed with air to convert the iron to ferric oXid and to form dilutechlorin for use in such second step while directing the remainder ofsaid vapors to the rst step of conversion.

Q. A process of treating in the dry way and at' elevated temperaturesmaterials containing iron in association with gangue for the recoverytherefrom of substantially pure iron oXid and other values, wherein suchmaterial is treated in a. first step with dilute ferric' chlorid vaporsto convert the iron to ferrous chlorid, the temperature lin said firststep being maintained above that temperature at which ferrie chloridwill condense from the dilute .vapor mixture brought to` said step andat the lsame time sufficient to insure volatilization of any sulfurfreed in said first step, and wherein `the ferrous chlorid in a secondstep is further chlorinated to ferrie chlorid vapors by the action ofdilute chlorin, the chlorid vapors so formed being separated from thegangue' and any non-,ferrous chloride formed and split into a majorfraction which is led to the'first chlorinating step above mentioned andthe minor fraction is burned with air to ferrie oXid, which isseparated, and to dilutel chlorin containing inert gases, which isreturned and used in the second or ferrous chlorid chlorinating step.

3. A cyclic chlorination process for treating materials containing ironin combination with sulfur which comprises treating such a material in afirst step with dilute ferrie chlorid vapors to displace sulfur andconvert the iron to ferrous chlorid, the temperature insaid first stepbeing maintained above that at lwhich ferrie chlorid will condense fromthe dilute vapor mixture brought to said step and at the same time abovethat temperature at which therdisplaced sulfur Will exist formed Withair to convert the iron content thereof to ferric oxid and to formdilute chlorin for use in such second step while directing the remainderofv said vapors to the first step of conversion.

4. A process of treating in the dry Way and at elevated temperaturesmaterials containing iron in combination with sulfur for the recovery ofsulfur and substantially pure iron oxid, wherein such material istreated in one step with dilute ferrie chlorid vapors in such amount andat such an elevated temperature that sulfur is displaced as such withformation of ferrous chlorid and the sulfur is volatilized as displacedand is removed as vapors in admixture with the inert diluent introducedwith said chlorid vapors, and wherein the ferrous chlorid is furtherchlorinated in another step to ferri-c chlorid vapors by the action ofdilute chlorin, the chlorid vapors so formed being split into a majorfraction Which is led to the sulfurdisplacing step above mentioned andthe minor fraction is burned with air to ferrie oxid, which isseparated, and to dilute chlorin containing inert gases, which isreturned and used in the ferrous chlorid chlorinating step.

5. A cyclic chlorination process for treating materials containing ironin combination with sulfur Which comprises treating such a material in afirst step With dilute ferric chlorid vapors to displace sulfur andconvert the iron to ferrous chlorid, the temperature in said first stepbeing maintained above that at Which ferrie chlorid will condense fromthe dilute vapor mixture brought to said step and at the same time abovethat temperature at which the displaced sulfur will exist other than asvapors in the presence of the inert diluent introduced wit-h the ferriechlorid vapors used in said first step; voiding the sulfur as vapors inadmixture With the inert gas accompanying the ferric chlorid used in thesaidl conversion step at temperatures at which ferrous chlorid has noappreciable vapor pressure; then further chlorinating the ferrouschlorid to ferrie chlorid vapors by the action of dilute chlorin, andburning part of the ferrie chlorid vapors so formed with air to convertthe iron content thereof to ferrie oxid and to form dilute chlorin foruse in such second step While directing the remainder of said vapors tothe first step of conversion.

6. A cyclic chlorination process for treating material containing ironand non-ferrous metal values in combination with sulfur which comprisestreating such a material in a first step with dilute ferrie chloridvapors to. displace sulfur and convert the ironv to ferrous -chlorid andother chlorinatable metals present to chlorid form, the temperature insaid first step being maintained above that at which ferrie chlorid willcondense from the dilute yvapor mixture brought to .sa-id step and atthe same time above that temperature at which the displaced sulfur willexist other than as vapors in the presence of the inert diluentintroduced with the ferrie chlorid vapors used in said first step;voiding the sulfur as vapors in admixture with the inert gasaccompanying the ferric chlorid used in the said conversion step attemperatures at which ferrous chlorid and `the nonferrous chloridspresent haveno appreciable vapor pressures; then treating theferrouschlorid ina second step of conversion with dilute chlorin to form ferricchlorid, volatilizing off the ferrie chlorid, leaving the gangue and theaforesaid non-ferrous chlorids substantially free from iron chlorids andiron oxid, and burning part of the ferrie chlorid vapors so formed withair to convert the iron content thereof to ferrie oxid and to formdilute chlorin for use in such second step While directing the remainderof said vapors to the first step of conversion.v

In testimony whereof, I have signed my name to this specification this22nd day of October, 1929. 1

ERNEST V. WESCGTT.

